Relationship between jack pine growth and site variables in New Brunswick plantations

Mean and dominant tree heights were determined on 28 sample plots within 18 jack pine (Pinusbanksiana Lamb.) plantations varying in age from 6 to 16 years. An average dominant tree was removed from each plot for stem analysis. The height versus age data were used to determine 2-, 3- and 4-year growth intercepts in each sample tree. Growth intercepts were positively correlated with foliar concentrations of nitrogen, phosphorus, and potassium, total nitrogen concentration in the main rooting layer of the mineral soil, as well as soil physical parameters associated with good drainage. Depth of forest floor and Ae horizon, clay content, bulk density, and drainage class were negatively correlated with growth. Close correlations were also revealed for site occupancy by ericaceous ground cover species and growth intercepts. The numerous site variables included in this study were reduced to five factors with significance to jack pine growth: (i) ericaceous cover - forest floor, (ii) drainage, (iii) extractable P, (iv) exchangeable K, and (v) Ae horizon development.